Treating hydrocarbon oils



Jan. 27,- 1942. R. F. RUTHRUFF ET AL 2,271,096

I TREATING HYDROCARBON OILS Filed Dec.- 29, 193'7 INVENTORS ROBERT E RUTHRl/FF CHARL 6 E FE (LHTf R ATTORNEY Patented Jan. 27, 194-2 TREATING HYDROCARBON, OILS Robert F. Ruthrufi, Nutley, N. J., and Charles F.

Feu'chter, Hammond, Ind., assignors to Standard Oil Company, Chicago, 111.,

of Indiana a corporation Application December 29, 1937, Serial N01. 182,192

s Claims. (01. 196-49) This invention relates to methods of treating hydrocarbons to convert higher boiling hydrocarbons into lower boiling hydrocarbons.

According to this invention a charge of relatively heavy oil is passed 'through a heatingzone or coil wherein it is heated to a cracking temperature and maintained under atmospheric pressure or slightly greater, and the heated products are then passed to a coking chamber or drum wherein vapors are separated from liquid constituents which remain in the coking chamber. Heavy constituents in the coking chamber are decomposed by the contained heat of the heated products into vapors and a coke residue which collects in, the coking chamber or drum. Vapors including the vapor products formed by the coking action in the coking chamber pass upwardly in the coking chamber and are passed to a fractionating tower wherein they are fractionated to separate heavy condensate oil such as a heavy gas oil and light reflux" condensate such as a light gas oil from a light distillate containing gasoline constituents.

The light reflux condensate is passed through a cracking zone wherein it is maintained under superatmospheric pressure and relatively high temperature conditions to effect the desired extent of cracking into lower boiling hydrocarbons containing gasoline constituents. The products from this cracking zone are separated into a liquid residue and vapors. A portion or all of the liquid residue may be mixed with the charge of relatively heavy oil passing through the heater first mentioned for conversion into coke and vapors.

The separated vapors are fractionated to separate a light distillate having the desired. boiling range from a light condensate oil such as a light gas oil. The light reflux condensate is preferably recycled through the cracking zone for further cracking treatment.

The heavy condensate oil separated from the vapors leaving the coking'chamber or drum is passed through a viscosity breaking zone wherein it is maintained under superatmospheric pressure and at an elevated temperature to produce a relatively large yield of intermediate constituentssuitable for further cracking to produce gasoline constituents. The products leaving the viscosity breaking zone are separated into liquid residue and vapors, the vapors being fractionated to separate a heavy condensate oil such as a heavy gas oil, a portion of which may be recycled through the viscosity-breaking zone for further cracking, from a light reflux condensate such as light gas oil which is preferably passed through the, cracking zone for conversion into lower boiling hydrocarbons containing gasoline constituents.

A portion or all of the liquid residue and a portion or all of the heavy condensate oil separated from the products leaving the viscosity breaking zonemay be mixed with the relatively heavy charging oil for passage through the heater first mentioned for conversion into coke and vapors in the coking chamber. a

In the drawing there is represented a diagrammatic illustration showing an apparatus suitable for practicing the process of the invention.

Referring now to the drawing, the reference character I0 designates a pump for forcing a relatively heavy charging oil through a line I? and through heating zone or coil I4 in a furnace or heater l6 wherein the heavy oil is raised to a cracking temperature and is maintained under atmospheric pressure or a pressure I slightly greater than atmospheric. The heavy oil is passed. through the heating zone or coil [4 at a velocity to prevent deposition of coke therein. The time of contact in the zone It is relatively short so that although. cracking temperatures are reached, no substantial amount of cracking will take place in the heating zone I4. The heated products are passed through line l8 into a coking chamber or zone l9 maintained at a suitable coking temperature wherein separation into vapors and liquid constituents is effected and coking of heavy constituents occurs. While 'only one coking chamber has been shown in the drawing it is to be understood that a plurality of such coking chambers is preferably used. The heated products passing through line [B may be passed through the branch lines 20, 22 and 24 into the coking chamber l9.

Liquid constituents remain in the coking chamber l9 and heavy constituents are decomposed by the contained heat of the heated products into'vapors and a coke residue which collects in the coking chamber. The coke residue may be removed in any suitable manner through manway 26. The vapors including the vapor products formed in the coking action in the cok- .ing chamber pass upwardly through line 28 into sate such as a light gas oil from a light distillate containing gasoline constituents.

pass overhead through line 32 and are cooled The vapors and condensed by passing through condenser 34, the distillate being collected in a receiver 36 having a valved gas outlet 38 and a valved liquid outlet 40. The light reflux condensate collects on trapout tray 42 having a hood 44. The heavy condensate oil is withdrawn from the bottom of the fractionating tower 30 and passed through line 46 by pump 48 through a viscosity breaking zone or coil 50 in heater or furnace 52 as will be later described in more detail.

The light reflux condensate collecting on trapout tray 42 is withdrawn therefrom and is passed through line 54 by pump 56 through a cracking zone or coil 60 in heater or furnace 62 wherein it is maintained under superatmospheric pressure and high temperature conditions in order to effect the desired extent of cracking thereof to produce lower boiling hydrocarbons containing gasoline constituents. The cracked products leave the cracking zone or coil 60 through line 64 having a pressure reducing valve 66 into an evaporator or separating zone 68 wherein aseparation into vapors and liquid residue occurs. A quench oil may be introduced through line 69.

The liquid residue is withdrawn from the'bottom of the evaporator or separating zone 68 through line I0. A portion of the liquid residue may be passed through line I2 by pump I4 and mixed with the relatively heavy charging oil passing through line I2 to be heated in the heating zone or coil I4 and the heated products then passed to the coking chamber for separation of vapors and for conversion of the mass into vapors and coke residue.

The separated vapors leave the top of the evaporator or separating zone 68 through line 16 and are passed to a second fractionating tower 18 wherein they are fractionated to separate relatively light condensate oil from a light distillate containing gasoline constituents. The vapors remaining after fractionation leave the top of the fractionating tower I8 through line 80 and are cooled and condensed by being passedthrough condenser 82, the distillate being collected in a receiver 84 having a valved gas outlet 86 and a valved liquid outlet 88. The light condensate oil is withdrawn from the bottom of the fractionating tower I8 and passed through line 90 by pump 92 for recycling through the cracking zone or coil 60 for further cracking.

The heavy condensate oil from the bottom of the first fractionating tower 30 which is passed through line 46 is passed through the viscosity breaking zone or coil 50 wherein it is maintained under superatmospheric pressure and at an elevated temperature to produce a relatively large yield of intermediate constituents suitable for further cracking to produce lower boiling hydrocarbons containing gasoline constituents. The products leaving the viscosity breaking zone or coil 50 are passed through line 94 preferably having a pressure reducing valve 96 into a second evaporator or separating zone 98 to separate vapors from liquid residue. is withdrawn from the bottom of the evaporator or separating zone through line I and a portion or all of the liquid residue may be passed through line I02 by pump I04 and mixed with the heavy charging oil passing through line I2 to be further heated in the heating zone or coil I4 and the heated products then passed to the coking chamber for separation of vapors and for conversion of heavy constituents into coke residue and vapors.

The vapors from the evaporator or separating The liquid residue zone 98 are passed through line I06 into a third fractionating tower H0 wherein they are fractionated to separate heavy condensate oil and light reflux condensate from a light distillate containing gasoline constituents. The vapors leaving the top of the third fractionating tower IIO are passed through line II 2 and are cooled and condensed by being passed through condenser II 4, the distillate being collected in a receiver II8 having a valved gas outlet I and a valved liquid outlet I22.

The light reflux condensate is collected on trapout tray I26 having a hood I30 and is withdrawn therefrom and passed through line I34 by pump I36. This light reflux condensate is preferably mixed with the charge passing to the cracking zone or coil 60 for further cracking treatment therein.

The heavy condensate oil is withdrawn from the bottom of the fractionating tower H0 and passed through line I 38 by pump I 40 for recycling a portion thereof through line I4I to the viscosity breaking zone or coil for further cracking treatment therein, and the rest of the heavy condensate oil is passed through line I42 for passage to the heating coil or zone I4 and then converted into coke residue and vapors in coking chamber I9. The heavy condensate oil passing through line I42 may be mixed with the liquid residue passing through line I02 or with the heavy charging oil passing through line I2 and the mixture passed to the heating zone or coil I4. Instead of passing part of the heavy condensate oil through the viscosity breaking zone or coil 50 and the rest through the heater I4, all of the heavy condensate oil may be passed through the Viscosity breaking zone or coil 50, or all of the heavy condensate oil may be passed through heater I 4.

A typical operation of one embodiment of the invention will now be given but it is to be understood that the invention is not restricted thereto. A relatively heavy charging oil such as reduced crude oil or other residual oil is passed through the heating coil or zone I4 wherein it is heated to about 840 to 950 F. and maintained under a pressure from atmospheric to about pounds per square inch. The heated products are introduced into the coking chamber I9 which has preferably been preheated to at least 650 F. and preferably higher. The coking chamber I9 is preferably insulated to prevent heat loss. The

coking chamber I9 during the operation is maintained at a pressure from atmospheric to about 60 pounds per square inch and at a suitable coking temperature of about 780 to 840 F.

In the coking chamber heavy constituents are decomposed to coke residue by the contained heat of the heated products, and vapors are separated. The vapors are fractionated in the fractionating tower 30 to separate heavy condensate oil from light reflux condensate. The heavy condensate oil is passed through the viscosity breaking zone or coil 50 wherein it is maintained under a pressure of about '75 to 500 pounds per square inch, preferably about 400 pounds per square inch, and at a temperature of about 850 to 950F., preferably about 940 F. The heavy condensate oil is maintained under these conditions for the desired period of time to efiectconversion into a relatively large yield of intermediate constitu- A portion or all of the condensate oil from. the bottom of the third fractionating tower H0 may be mixed withthe heavy condensate oil; cosity breakingzone to a separating zone to sepapassing through the viscosity breaking zone or coil 50 for cracking treatment along with the heavy condensate oil;- or a portion or all of the condensate oil from tower I H] may be mixed with liquid residue from evaporator 98 for passage to the heating coil or zone l4.

The products leaving the viscosity breaking zone or coil 50 are passed to the evaporator or separating zone 98 which is maintained under apressure of about 10 to 50 pounds per square inch. The viscosity broken products are separated into liquid residue and vapors, the vapors being fractionated to separate heavy condensate oil, which may be recycled through the viscosity breaking zone or coil 50 or directed to heating coil 14, as just described, from a light reflux condensate Which is passed through the cracking zone or coil 60 as will be presently described. A portion or all of the liquid residue from the bottom of the evaporator or separating zone 98 is directed to the heating coil or zone M for further treatment therein.

The light reflux condensate from the fractionating tower 30 passing through line 54 and light reflux condensate from fractionating tower H passing through line I34 are passed through the cracking zone or coil 60 wherein they are maintained under a pressure of about 200 t 1000 pounds per square inch, preferably about 750 poundsper square inch and at a temperature of about 925 to 1100 F., preferably about 975 F. to efiect the desired extent of cracking. The cracked products are passed to the evaporator or separating zone 68 which is maintained under a pressure of about 200 to 300 pounds per square,

inch to separate vapors from liquid residue. The vapors are fractionated in the fractionating tower T8 to separate a light distillate having the desired boiling range from a condensate oil which is passed through line 90 and recycled through the cracking zone 60 for further cracking treatment.

While no means for providing reflux liquid for the top of the fractionating towers or below the trap-out trays therein have been shown in the drawing, it will be understood that reflux liquid is used during the fractionation of the vapors in the fractionating towers according to well known fractionating practice. 1

While one embodiment of the invention has been described, it is to be expressly understood that the invention is not restricted thereto and various modifications and adaptations thereof may be made without departing from the spirit of the invention.

We claim:

1. A process for converting higher boiling hydrocarbons into lower boiling hydrocarbons which comprises primarily heating a crude residual charging stock to a cracking temperature and passing the heated products to a coking zone wherein the heated products are maintained at a coking temperature by their contained heat to form vapors and coke residue, fractionating the vapors to separate a heavy condensate oil from light reflux condensate, passing the heavy rate vapors from liquid residue, fractlonating the last mentioned vapors to separate heavy condensate oil from light reflux condensate; recycling at least a portion of the last mentioned heavy condensate oil through said viscosity: breaking zone, combining the lightreflux condensates and passing the mixture through a separate cracking zone wherein it is maintained under superatmospheric pressure and high temperature conditions t efiect the desired extent of cracking thereof into lower boiling hydrocarbons includ-.

ing gasoline constituents, separating the prod.- ucts leaving said separate cracking zone into vapors and liquid residue, and fractionating the last mentioned vapors in a separate fractionating zone to separate condensate oil from light distillate having the desired boiling range.

2. A process for converting higher boiling hydrocarbons into lower boiling hydrocarbons which comprises primarily heating a crude residual charging stock to a cracking temperature and passing the heated products to a coking zone wherein the heated products are maintained at a coking temperature by their contained heat to form vapors and coke residue, fractionating the vapors to separate a heavy condensate oil from light reflux condensate, passing the heavy condensate oil through a viscosity breaking zone wherein it is subjected, entirely separately from the crude residual charging stock, to superatmospheric pressure and relatively high temperature conditions to produce a relatively high yield of intermediate constituents suitable for further cracking to produce gasoline constituents, passing the products from said viscosity breaking zone to a separating zone to separate vapors from liquid residue, fractionating the last mentioned vapors to separate heavy condensate oil from light reflux condensate, passing the light reflux condensates through a separate cracking zone wherein they are maintained under superatmospheric pressure and high temperature conditions to effect the desired extent of cracking thereof into lower boiling hydrocarbons including gasoline constituents, separating the products leaving said separate cracking zone into vapors and liquid residue, fractionating the last mentioned vapors in a separate fractionating zone to separate condensate oil from light distillate having the desired boiling range, and recycling the last mentioned condensate oil through said cracking zone.

3. A process for converting higher boiling hydrocarbons into lower boiling hydrocarbons which comprises primarily heating a crude residual charging stock to a cracking temperature and passing the heated products to a coking zone wherein the heated products are maintained at a coking temperature by their contained heat to form vapors and coke residue, fractionating the vapors to separate a heavy condensate oil from light reflux condensate, passing the heavy condensate oilthrough a viscosity breaking zone wherein it is subjected, entirely separately from the crude residual charging stock, to superatmospheric pressure and relativelyhigh temperature conditions to produce a relatively high yield of intermediate constituents suitable for further cracking to produce gasoline constituents, passing the products from said viscosity breaking zone to a separating zone to separate vapors from liquid residue, fractionating the last mentioned vapors to separate heavy condensate oil from light reflux condensate, combining light reflux condensates and passing the mixture through a separate cracking zone wherein it is maintained under superatmospheric pressure and high temperature conditions to effect the desired extent of cracking thereof into lower boiling hydrocar bons including gasoline constituents, separating the products leaving said separate cracking zone into vapors and liquid residue, and fractionating the last mentioned vapors in a separate fractionating zone to separate condensate oil from light distillate having the desired boiling range,

4. A process as defined in claim 3 wherein the last mentioned condensate oil is recycled through said cracking zone while said heavy condensate oil separated from the vapors of the viscosity breaking operation is recycled to the viscosity breaking zone.

5. A process as defined in claim 3 wherein at least a portion of the liquid residue derived from the products leaving said viscosity breaking zone is heated and passed to said coking zone wherein vapors are separated and heavy constituents are converted into vapors and coke residue.

6. A process as defined in claim 3 wherein at least a portion of the last mentioned liquid residue is heated and passed to said coking zone wherein coking of heavy constituents occurs and vapors are separated from coke residue.

ROBERT F. RUTHRUFF. CHARLES F. FEUCHTER. 

